Before purchasing paints, buyers typically are given a fan deck or palette comprising hundreds or thousands of paint chips, which represent a small portion of the available paint colors. The paint chips typically measure about 1¼ inch by 2 inches, and recently, the buyers can purchase larger paint chips of about 12 inches by 12 inches to assist the buyers with the mental projection of the colors to the walls. Additionally, the buyers may purchase small containers of about 2 ounces of the desired paints to paint larger swatches on the walls. Typically, the buyers start with small paint chips to narrow the choices and then move to larger paint chips and/or sample paints before choosing the final paint colors.
Recently, paint viewing or paint selection software, such as Benjamin Moore® Paints' Personal Color Viewer™ (“PCV”) available either on the World Wide Web or as CD-ROM, has improved the paint selection process for the buyers. The PCV software displays on a computer screen a number of standard interior rooms with furniture, e.g., living room, dining room, bedrooms kitchen and bathroom, as well as the exteriors of a dwelling. The buyers can change the colors of the room, including ceiling, trim and upper and lower walls, at will to project the colors to the entire room. Additionally, digital images of the buyers' own dwellings can be manipulated by the PCV software to display the desired colors.
One possible drawback of the paint selection software is that the images are typically displayed on computer screens, which are limited to combinations of three RGB primary colors (red, green and blue), or four CMYK primary colors (cyan, magenta, yellow and black) for printers. Only a limited number of colors can be displayed and viewed when only three or four primary colors are used. Similarly, a fan deck can only display several thousands of colors, while more than ten thousand paint colors are available.
Furthermore, both paint selection software and physical color chip fan deck cannot control the ambient light when paint colors are viewed by the consumers. It is known that colors can look different under different ambient illuminations, i.e., to a consumer a particular color can look one way under one ambient light and look differently under a different ambient light. This phenomenon is known as “color inconstancy.” Color inconstancy is the change in color of a single physical color under different lights. For example, the colors we see outdoors are illuminated by the sun with a wide range of color temperature from sunrise to sunset. Indoor illumination or artificial light is rarely as bright as natural sunlight. Illumination is an important factor in viewing colors and the intensity of the environment has a measurable effect on colors viewed by people. This effect explains why a consumer sometimes thinks that a new paint applied at home looks different than that paint had looked at the store.
Another drawback of paint selection software and color chip fan deck is that they may be subject to “source metamerism.” Two or more paints may have the same color appearance under one ambient lighting condition, but may appear to be different color under another ambient lighting condition. This is caused by the fact that color pigment combinations of the paints can be different from each other. Paint selection software and color chip fan decks do not have the ability to vary ambient lighting condition.
The patent and scientific literatures disclose a number of attempts to address the representation of colors. A computer screen based color display system is disclosed in U.S. Pat. No. 6,717,584 B2. This reference discloses a method and apparatus for visualizing virtual paints on a computer-generated automobile. Reflectivity of the paints, which is caused by metal flakes or special effect pigments in the paints, and the angle at which the automobile is viewed affect the display of the virtual paints on the computer screen.
The walls in some public buildings, such as airports, have the capability of changing colors due to the lights that are projected on to them. For example, some of the walls in the Detroit airport are illuminated by LEDs. The colors and patterns on these walls can be changed at will by altering the outputs of the LEDs. No attempt is made to match the displayed color to the color of a real object or device independent color, and uniformity of colors on the walls is not a concern.
Methods of representing colors by devices are also described in U.S. Pat. Nos. 6,259,430, 6,985,163, 7,161,311, 7,186,003 and 7,161,313. The '430 patent discloses a method of displaying colors that allegedly can control the metameric effect. This method divides the radiation spectrum into at least four wavelength bands and selects a single representative wavelength in each band. The intensity of each representative wavelength is selected, and a plurality of radiation beams at the selected intensities and representative wavelengths are generated and combined to produce the desired color. The '163 patent discloses a color display method and apparatus for displaying a mixed color produced by mixing a plurality of individual colorants in a predetermined ratio. The '311 patent discloses devices such as light fixtures that combine multiple light emitting diodes (LEDs) to form a light source. The '311 patent discusses using a hollow cylindrical section to help mix the lights emitting from the LEDs. Similarly, researchers at the National Institute of Standards and Technology have used a hollow sphere to mix lights from a number of LED heads that are directly connected to the sphere. See “LED-based Spectrally Tunable Source for Radiometric, Photometric and Colorimetric Applications,” I. Fryc, S. Brown, G. Eppeldauer and Y. Ohno, Optical Engineering 44(11), 111309 (November 2005) and “Spectral Matching with an LED-based Spectrally Tunable Light Source,” I. Fryc, S. Brown and Y. Ohno, Proc. of SPIE 5941, 594111 (2005) (hereinafter “the Fryc publications”). The '003 and '313 patents discuss using processor-controlled LEDs with diffusing materials; e.g., transparent, translucent or semi-transparent materials, to produce color-changing effects.
U.S. Pat. Appl. Pub. No. 2006-0155519 A1 (hereinafter the '519 application) discloses a full-size room that can uniformly display machine-generated colors on its walls to allow customers to view paint colors on full-size walls. The machine-generated colors are mixed in diffusers before illuminating the full-size walls. The disclosure of the '519 application is incorporated herein by reference in its entirety.
However, there remains a need in the art for a color management method that may accurately match a batch color, represented by a light mixing system, to a standard color.